M-Roadster rear drive train and suspension swap
 

Hi,

I was able to secure a complere M-Roadster complete rear drive train. Basically the whole thing from the diff to the and all the parts inbetween. At some point I may do an M50/M52 engine swap but wondered what the differences in the old differential and new differential would do. Not sure what the old one is (stock for a basic 97 318ti) vs. 3.25 one on the M-Roadster. Will my exisiting 4 cylinder have any problems driving it? What would be the gain/loss.

Yeah I know the rear brakes are different and all that... that's a different issue. Just need to know about the diff right now. Also will the exisitng drive shaft just bolt up. Later, if I do an engine swap do you keep the 318ti drive shaft or do you need a different one. I may have the chance to pick up the M-Roadster drive shaft too but dont want to if it's not needed for a later engine swap.

Any help would be appreciated, especially from someone who has also done this kind of swap.

Thanks

David

the Mroadster complete rear end is a direct bolt-on. Once you have that install, Your pretty much a good candidate for a 6 cyl swap. You may need to find a way to get the emergency brake working though.

What ever tranny you wil be using you will have to mate with that driveshaft.(e.g.) 318ti tranny will require 318ti Drive shaft, m3 zf tranny will require M3 driveshaft.
good luck. keep us updated. by the way how much did you happen to pick the rear end for?

nice find! stock ratio (assuming you have a 5-speed manual) is 3.45 so you'll be even slower than stock! you'll have a theoretical higher top end (assuming the 4 can get it there) ... except for being electronically limited to something around 116-120mph. i'm also assuming that the M-roadster one is a LSD so you'll gain there as well if you have an open diff.

Bolt on M-Roadster rear end
 

Thanks for the confirmation on the setup. I have disassembled and reassembled the eBrake stuff before so I am reasonably sure that I can pull off using the existing one.

I can't say what I paid for the complete rear end but, if you can find one, one should expect to pay over 2K.

Ratio on M-Roadster Diff
 

Yeah that is an issue. I may consider pulling my 3.45LSD from my e36 M3 track car and using that then upping my track car diff to a 3.64 or 3.75. Not sure If I can just swap the diff (and just swap covers) or if I need to swap internals.